The Liberals and Nationals are busy tussling over water but they’re not the only ones. Irrigators, environmentalists and communities all want their share. And as Bill Heffernan points out, you can’t possibly please everyone

As an El Niño weather pattern approaches, and with it the likelihood of another drought, the bitter divisions of water politics are re-emerging – and with them the threat of ecological devastation, the desperation of farm communities and South Australia’s deep-seated fears about water supply.

In fact these fears have been allegedly put to rest so many times in the past few decades it’s hard to keep count. Twenty-six years ago, as a cub reporter, I travelled with Bob Hawke to Wentworth in far western NSW to hear him deliver what he modestly referred to as “the world’s greatest environment statement”. That involved spending $500m and planting 1bn trees, and marked the first mainstream recognition that the over-allocation of farming and irrigation water and general mismanagement meant things were going terribly wrong with the nation’s most economically important river system.

In 2004 the federal government and the states set aside $1bn to “give back” 500 gigalitres (about one Sydney Harbour full) of the over-allocated Murray-Darling water to the environment. That didn’t work very well either, so in 2007 a new water minister called Malcolm Turnbull put together a $10bn plan to solve the problem, which was subsequently recast by the Rudd government, with a $2.8bn top-up. Then came the 2011 plan. Now it, too, is under pressure.

Like all truly difficult problems this is a fight between genuine inter-related – but competing – interests.

The Darling river in Louth, New South Wales, in 2008. The southern Murray-Darling basin is forecast to suffer a 15% decline in rainfall, equivalent to a 35% decline in runoff. Photograph: Dean Lewins/AAP

On the environmental side, successive governments had unquestionably over-allocated water rights in a way that was proving fatal for the ecology. But how much water needs to be “put back”? The CSIRO found 3,500 to 4,000 gigalitres at a minimum. The draft Murray-Darling basin plan said 3,000 gigalitres. The final compromise agreement, struck by Burke, said 2,750. Late last year, as rural anger rose, the parliament legislated that a maximum of 1,500 gigalitres could be achieved through water “buybacks” , with the rest coming from water saved by commonwealth spending on more efficient water use by farmers or more efficient use for the environment. It’s not clear that this is going to be possible.

And to complicate things further, from the outset, politicians have been promising different things to different people. Former prime minister Julia Gillard did a side deal with South Australian premier Jay Weatherill to add another 450 gigalitres to the 2,750 – adding $1.7bn to get that extra water and make sure the mouth of the Murray was open 95% of the time. She also did a side-side deal with Victoria and NSW that the extra 450 gigalitres would be the subject of a review, which might reduce the environmental water by 650 gigalitres. So voters in South Australia were told the plan would deliver up to 3,200 gigalitres, while NSW irrigators were told it was likely to be as low as 2,100. The “review” is to be decided next year.

On the farming side the consequences and fears are also dire.

The former Labor government bought back a lot of water during the drought years, with some financially-distressed farmers selling permanent water licences on the assumption they could buy temporary licences in the future. With a drought looming, the laws of supply and demand (and the many speculators in the largely unregulated and unpoliced water market) are making those permits unaffordable.

The Liberal backbencher and member for the Victorian seat of Murray, Sharman Stone, says the buybacks are also having knock-on effects, for example leaving so many dairy farms in her region “dried out” and unproductive, that it is threatening dairy manufacturing investment. She says the Murray-Darling is losing $5m a day in food production because of reduced water availability.

Stone also wants the $1.7bn agreement with South Australia revisited, saying some of that money might be better spent just turning on Adelaide’s desalination plant.

The deep fears of rural communities are percolating into the federal political process in other ways.

Water is now a live-or-die issue for the National party, which is why it demanded the portfolio switch from the environment minister to the agriculture minister (Barnaby Joyce) in its Coalition agreement with Malcolm Turnbull. It also explains the strange spat over Joyce’s formal job description, in which he demanded his junior minister, South Australian Liberal senator Anne Ruston, have no say over the day-to-day decision making on water.

One of Joyce’s first decisions will be whether he accepts a recommendation in a recent review to ditch the requirement that any money earned by the commonwealth from water trading be spent on more buybacks, and whether he accepts demands for the commonwealth to be able to sell “excess” water to irrigators, increasing supply and reducing temporary water prices. Environmentalists see those ideas as the thin end of the wedge, a further erosion of the water available for the environment.

And pressure on the Nationals will only intensify with a Senate committee instigated by the crossbench senators and taking evidence throughout regional areas. Those senators are championing a grassroots plea that the Murray-Darling plan be “paused”, whatever that might mean.

Politicians, he said, had to stop making contradictory promises they couldn’t keep. Promising everyone more water was like promising everyone free beer, it only made you popular until they realised you couldn’t do it. He cited figures suggesting the southern Murray-Darling basin would suffer a 15% decline in rainfall, equivalent to a 35% decline in runoff.

“The science is warning us” he said, and it was time for politicians to stop making promises that really amounted to playing politics with the people whose livelihoods depend on Murray-Darling water, and also with the environment.